SYK and asthma: Moreover, Syk is a key activator of signaling downstream of multiple surface receptors implicated in asthma, supporting a key role for Syk signaling in mediating allergic airway responses [46,47] Thus, kaempferol may abrogate COX2-mediated airway thickening by hampering Syk-PLCγ-cPLA2 signaling of antigen-exposed mast cells.